Synchronization of audio and video signals in an audio/visual (A/V) transmission is an important measure of the quality of the transmission. However, despite (and in some cases due to) advances in A/V transmission systems, such as digital television, high-definition television and satellite television, A/V synchronization remains problematic.
For example, in typical digital television transmissions, audio and video signals are each compressed and decompressed with different delays and latencies. The audio and video signals thus need to be re-synchronized at each point where content is modified, retransmitted or displayed in order to ensure a seamless A/V transmission. Some existing A/V transmission systems, including some digital video, digital audio and MPEG-2 transport systems, provide time code references for synchronization of audio and video signals; however, the time code references are typically only applied in production facilities and are not carried throughout the entire broadcast chain (which typically ends with the consumer). Thus, A/V synchronization of the end product is not assured. Other proposed solutions have had more success in terms of providing proper A/V synchronization, but significant complexity has made such solutions cost prohibitive.
Therefore, there is a need in the art for a method and apparatus for measuring and/or correcting audio/visual synchronization.